Drawing FIG. 1 schematically indicates a prior art clutchable pulley system (10) that conventionally utilizes idler-pulleys (e.g. 14, 19). An idler-pulley (19) is employed for intermittently frictionally entraining an annular second-belt (18) about the second-groove (13N) of a plurally-grooved transfer pulley (13) whereby one or more secondary-load pulleys (16, 17, etc.) will become rotated from an annular first-belt (15) that is constantly driven by a power-source pulley (11). First-belt 15 is normally constantly frictionally trained about other pulleys having spatially fixed and mutually parallel axial shafts including: said power-source pulley 11 (having axial shaft 11A); at least one primary-load pulley (e.g. 12 having axial shaft 12A); and a first-groove 13M of transfer pulley 13 (having axial shaft 13A). Though the circumferential grooves (e.g. 13M, 13N) of such plurally-grooved transfer pulleys are usually spaced the same radial distance from its axial shaft (13A), for purposes of graphical clarity, the groove 13N for second-belt 18 is shown radially outwardly from the first-belt groove 13M. Second-belt 18, which is parallel to and herein behind first-belt 15, is normally loosely trained about the aggregate of: said transfer pulley 13 (e.g. at 13N); and one or more secondary-load pulleys (e.g. 16, 17, etc.). The secondary-pulleys have spatially fixed and mutually parallel axial shafts (e.g. 16A, 17A, etc.).
For such prior art systems (e.g. 10), controllable intermittent engagement of the second-belt (18) with the plurally-grooved pulley (13 at 13N) is conventionally accomplished by an idler-pulley (19) which is movable against the second-belt (18), as indicated by phantom arrow in FIG. 1. However, utilization of idler-pulleys (e.g. 19) for intermittently effecting engagement of a second-belt (e.g. 18) with a plurally-grooved transfer pulley and its associated secondary-load pulleys is fraught with serious disadvantages. For example, such utilization of idler-pulleys in intermittent abrupt contacts with the second-belt causes chafing, stretching, backside bending, belt cord wear, and other inimical stresses that seriously diminish belt life. Moreover, utilization of idler-pulleys requires substantial extra space for the clutchable pulley system that cannot be tolerated in certain space constraint situations e.g. within riding lawn mowers, etc.